JPH11300154A - Sulfur recovering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To completely oxidize S components into SO2 to restrain the discharge of slid S, unburned H2 S, and sulfuric acid mist. SOLUTION: In this sulfur recovering method, there are included a process 102 wherein a high temperature formed gas is subjected to heat recovery in a heat recovering part 2, processes 103, 104 wherein the formed gas is passed through a cyclone 3 and a char recovering part 4 respectively, a process 105 wherein HCl and some kinds else are removed in a washing part 5, a process 106 wherein COS is converted into H2 S by a COS converting part 6, a process 107 wherein the converted H2 S is concentrated and separated by a wet type gas purifier 7, a process 108 wherein H2 S is recovered in high concentration and is burned by air or O2 in a H2 S combustor 8 and the generated SO3 and unburned H2 S are reacted by a Claus reactor 9 to recover liquid S, a process 109 wherein the liquid S is completely burned by air or O2 , and a process 111 wherein the combustion gas is led to a limestone gypsum desulfurizer 12 to recover sulfur sulfide in the combustion gas as gypsum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to hydrogen sulfide (H
Regarding the treatment of ₂ S), in particular, the liquid S obtained by the Claus reaction is completely burned with dry air or oxygen (O ₂ ) to suppress the formation of sulfuric acid mist, and the sulfur (S) content is desulfurized by the limestone gypsum method. To a sulfur recovery method.

[0002]

2. Description of the Related Art In recent years, attempts have been made to use gasification products of coal and heavy oil as chemical raw materials and fuels for power generation. However, for example, coal contains sulfur (S), and this sulfur is converted into H ₂ S and carbonyl sulfide (COS) by gasification. The concentration of these sulfur compounds is governed by the S content in the raw material, it contains several hundreds to several thousands ppm of sulfur compounds in the product gas by gasification (mainly H ₂ S) is, It is necessary to desulfurize this sulfur compound from the aspect of pollution control in the gasification utilization process. Conventionally, H ₂ S is concentrated using an alkanolamine absorbing solution or the like in many chemical processes, and then recovered as solid S using the Claus reaction. On the other hand, there have been attempts to perform desulfurization at a high temperature and omit the gas cooling and reheating step.

A typical example of a sulfur recovery method for purifying generated gas generated by coal gasification will be described with reference to FIG.
A step 101 of discharging the high-temperature generated gas from the gasifier 1;
A step 102 of recovering heat of the generated gas in the heat recovery section 2, a step 103 of passing the generated gas through the cyclone 3, a step 104 of recovering the char passing through the char recovery section 4, and a step of washing the hydrogen 5 (HCL) in the washing section 5. ) And some other trace elements besides ammonia (NH ₃ ) 10
5 and, if necessary, the COS converter 6 converts the COS to H _2.
Step 106 for converting to H ₂ S, step 107 for concentrating and separating the converted H ₂ S by the wet gas refining device 7, and gas for recovering H ₂ S to a high concentration and containing CO ₂ in the H ₂ S combustor 8. A step 118 of burning with air or O ₂ and assisting with a light oil burner if necessary,
120, a step 121 of leading the combustion gas to the limestone gypsum desulfurization unit 12 to recover the sulfur compound in the form of gypsum (CaSO ₄ ), and a step 122 of discharging the detoxified combustion gas from the chimney. Is done.

[0004] As the sulfur treatment, the concentration recovery of H ₂ S wet gas purification method has been put into practical use after being absorbed H ₂ S with an alkanolamine absorbing solution, etc., of another of the liquid After being led to a column and heated under reduced pressure to remove H ₂ S, it is recovered as elemental S by the Claus reaction.
The Claus method, in which the concentrated and recovered H ₂ S is combusted and recovered as solid S, has a problem in handling at power plants because the market conditions of the solid S are sluggish and dangerous. is there. On the other hand, the dry desulfurization method, iron, after reacting the H ₂ S to a metal oxide such as Ni, in an oxygen-containing gas H ₂ S
Is oxidized and regenerated as a metal oxide, but there are problems such as powdering of the desulfurizing agent, and there is a problem in reliability and it has not been put to practical use. Therefore, at this stage, it is better to adopt a wet gas purification method for H ₂ S enrichment and recovery from the generated gas and to develop a method of burning and enriching and recovering H ₂ S to process and recover S components. is there. As a sulfur content recovery method, sulfur content is burned with oxygen or air to form sulfur dioxide (SO ₂ ), and then recovered with a limestone gypsum desulfurization device. The problem here is to completely oxidize the S component to SO ₂ and not to discharge solid S, unburned H ₂ S and sulfuric acid mist.

[0005]

In the conventional sulfur treatment method, the Claus method, in which H ₂ S concentrated and recovered by a wet gas purifying apparatus is burned and recovered as solid S, is not suitable for the solid S market. Due to sluggishness, dangerous goods, etc., there is a problem in handling at power plants. on the other hand,
The dry desulfurization method has a problem such as pulverization of a desulfurizing agent, has a problem in reliability, and has not been put to practical use. Therefore, at this stage, it is better to adopt a wet gas purification method for H ₂ S concentration and recovery from the generated gas, and to develop a method of burning and recovering the concentrated H ₂ S to process and recover the S component. is there. Then, the S component is burned with oxygen or air to form SO ₂ and then recovered by a limestone gypsum desulfurization device. The task here is to completely replace S
Oxidation to O ₂ , not to discharge solid S, unburned H ₂ S and sulfuric acid mist.

An object of the present invention is to provide a sulfur recovery method which completely oxidizes S content to SO ₂ and suppresses emission of solid S, unburned H ₂ S and sulfuric acid mist.

[0007]

In order to achieve the above object, a sulfur recovery method according to the present invention is characterized in that H ₂ S is burned with oxygen or air, and the combustion gas is exchanged with a heat exchanger. SO
In sulfur recovery process for desulfurizing _2, unburned and SO ₂ H
_The liquid S recovered by the reaction with ₂ S is separated from water vapor, completely burned with dry air or oxygen, and the combustion gas containing SO ₂ is desulfurized by a limestone gypsum desulfurization device.

According to the present invention, by partially combusting H ₂ S with oxygen or air to produce a SO _2, reacting the unburned H ₂ S addition this SO _2, by Claus reaction liquid S obtain. Then, the liquid S is completely burned with dry air or oxygen. Thereby, even if the temperature of the combustion gas decreases while the combustion gas passes through the heat exchanger, the generation of sulfuric acid mist is substantially suppressed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A system configuration will be described as an embodiment of the present invention with reference to FIG. As shown in FIG. 1, hydrogen sulfide (H ₂ S) is burned with oxygen (O ₂ ) or air, and the combustion gas is heat-exchanged in a heat exchanger 11 to remove sulfur dioxide gas (SO ₂ ). In a recovery method, a liquid S recovered by a reaction between SO ₂ and unburned H ₂ S is separated from water vapor and completely burned with dry air or oxygen, and a combustion gas containing SO ₂ is subjected to a limestone gypsum desulfurization apparatus. It is configured to desulfurize in step 12.

That is, a step 101 for discharging the high-temperature product gas from the gasifier 1, a step 102 for recovering the product gas in the heat recovery unit 2, a step 103 for passing the product gas through the cyclone 3, and a char recovery unit 4 and a step 105 of collecting char through the washing section 5 and a step 105 of removing some trace elements other than HCL and NH _{3 in} the washing section 5.
And, if necessary, the COS conversion section 6 converts the COS to H ₂ S
Air and step 106 of converting, in the step 107 to concentrate separated by a wet gas purification device 7 the conversion was H ₂ S, the gas containing recovered vital CO ₂ and H ₂ S at a high concentration in the H ₂ S combustor 8 Or SO ₂ generated by combustion with O ₂ and unburned H ₂ S
108 in which the liquid S is recovered by reacting the liquid S in the Claus reactor 9 and then, the step 10 in which the liquid S is completely combusted by the complete combustor 10 with dry air or O _2.
9 and a step 1 of exchanging heat of the combustion gas with the heat exchanger 11
10, a step 111 of leading to the limestone gypsum desulfurization device 12 to recover sulfur sulfide in the combustion gas as gypsum, and a step 112 of discharging detoxified exhaust gas from the chimney.

As described above, the high-temperature product gas discharged from the gasification furnace 1 is recovered by the heat recovery unit 2 and then cooled by the cyclone 3.
After passing through the char recovery unit 4 and the washing unit 5, the HCL,
After removing some kinds of trace elements other than NH ₃ , COS is converted into H ₂ S by the COS converter 6, and H ₂ S is processed by the wet gas purifier 7. The gas containing CO _{2 from} which H ₂ S has been recovered at a high concentration is burned by air or O ₂ , and the generated SO ₂ and unburned H ₂ S are recovered as liquid S by a Claus reaction. Next, the liquid S is completely burned with dry air or O ₂ . The gas to be treated is heat-exchanged by the heat exchanger 11, and then guided to the limestone gypsum desulfurization unit 12, collected as gypsum, and the detoxified gas is discharged from the chimney to the atmosphere.

Next, the operation of the present embodiment will be described. Conventionally, H ₂ S in the product gas discharged from petroleum refining, coal gasification, etc. has been obtained by utilizing the reactions of the formulas (1) and (2).
₂ S is recovered as S. H ₂ S + 3 / 2O ₂ → SO ₂ + H ₂ O (Chemical formula 1) Catalyst: Bauxite or alumina 2H ₂ S + SO ₂ → 3S + 2H ₂ O (Chemical formula 2) According to the formula (1), H _{When the 2} S is burned and oxygen is lost, the remaining H ₂ S reacts with the SO ₂ generated according to the formula (1) to form a liquid S according to the formula (2). However, since the reaction rate of the chemical formula (1) is high and the reaction of the chemical formula (2) is slow, the reaction of the chemical formula (2) is accelerated by using a catalyst such as bauxide. The limestone gypsum desulfurization device is a reaction device that absorbs SO ₂ into the limestone slurry. For example, an excess oxygen is supplied to cause the reaction according to the chemical formula (1) to prevent the reaction according to the chemical formula (2) from occurring. Then, the liquid S is separated from the water vapor and completely burned according to the reaction of the chemical formula (3), whereby no water vapor is generated.
Therefore, even if SO ₃ is generated by the reaction of the chemical formula (4), the reaction of the chemical formula (5) does not occur. That is,
Sulfuric acid mist will not be generated in principle.

As described above, the S component is easily desulfurized as SO ₂ in a limestone gypsum desulfurization apparatus. Also, even if SO ₃ is present, it is not a sulfuric acid mist, so it is easily absorbed into limestone slurry and desulfurized. S + O ₂ → SO ₂ (formula 3) SO ₂ + 1 / 2O ₂ → SO ₃ (formula 4) SO ₃ + H ₂ O = H ₂ SO ₄ (formula 5) In the present invention, substantially Since no sulfuric acid mist is generated, there is no need to install an EP upstream or downstream of the limestone gypsum desulfurization apparatus.

H ₂ S is burned with air or oxygen, and the liquid S is separated from water vapor by the Claus reaction. The liquid S is completely burned with dry air or O ₂ . In this reaction, as shown in the chemical formula (3), since there is no generation of water vapor, even if SO ₃ is generated according to the chemical formula (4), the generation of sulfuric acid mist is substantially suppressed.

According to the present invention, since the liquid S obtained by the Claus reaction is completely burned with dry air or O ₂ , the generation of sulfuric acid mist can be eliminated, and the corrosion of the structural material or the installation of EP is not required. It is a process that has no environmental problems.

[0016]

According to the present invention, since the liquid S obtained by the Claus reaction is completely burned with air or O ₂ , the generation of sulfuric acid mist can be suppressed, and the corrosion of the structural material can be prevented. This has the effect of making the process environmentally favorable.

[Brief description of the drawings]

FIG. 1 is a process chart showing one embodiment of the present invention.

FIG. 2 is a process chart showing a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Gasifier 2 Heat recovery part 3 Cyclone 4 Char recovery part 5 Rinse part 6 COS conversion part 7 Wet gas purification device 8 H ₂ S combustor 9 Claus reactor 10 S complete combustor 11 Heat exchanger 12 Limestone gypsum desulfurization apparatus

Claims (1)

[Claims] 1. A by burning H ₂ S with oxygen or air and the combustion gas heat-exchanged in the heat exchanger, the sulfur content recovering method for desulfurizing SO _2, and H ₂ S of unburned and SO ₂ A method for recovering sulfur, characterized in that the liquid S recovered by the reaction is separated from water vapor, completely burned with dry air or oxygen, and the combustion gas containing SO ₂ is desulfurized by a limestone gypsum desulfurization device.